Finding the right codec

OK. I've got some HD footage on my hard drive. Some of it is Photo JPEG, some is HDV 720p30. (took me forever to find what codec it was.)
The Photo JPEG works fine. The HDV opens a big window with just black. I get the sound and duration, but just black.
Is there a way to get this HDV 720p30 codec to work on my PC? The footage was converted on my school's MAC. Do I need to find a MAC to convert it?

It doesn't answer the original question, but DVCProHD was brought up in the discussion. You can use FCP to convert your HDV footage to DVCProHD, can't you? If this was done on his schools Mac, and they have FCP, he could convert it to DVCProHD and use Raylight to edit on his PC. Otherwise he'll have to find another codec that's cross platform, and I'm not sure what that is. But I know DVCProHD is possible, hence my post.

OT: Does anyone else think it's a shame that codecs are still made that are not cross platform? Is locking a codec to Apple or PC really going to increase sales on either platform?

So far nothing's worked.
The camera records directly to the a hard drive. Then they use Compressor (I believe)to turn it into a format we can use it in the PC Lab. My guess is I've got the "raw" file that the camera spits out(JVC).
I haven't tried Raylight but you sound like you know what you're talking about.